Nucleic Acids

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					Nucleic Acids Melaku Michael (ethiomelaku2)
Polymers of Information

What determines primary structure of a protein?
 Gene – unit of inheritance that determines
the sequence of amino acids *made of DNA (polymer of nucleic acids)  Building blocks of nucleic acids are nucleotides *phosphate group, pentose sugar, nitrogenous base (A,T,C,G,U)

Figure 5.29 The components of nucleic acids

Nucleic Acids
Exist as 2 types : DNA and RNA

*DNA --

*double stranded (entire code) *sugar is deoxyribose *never leaves nucleus *bases are A,T,C,G *involved in replication and protein synthesis *single stranded (partial code) *sugar is ribose *mobile – nucleus and cytoplasm *bases are A,U,C,G *involved in Protein Synthesis

*RNA --

DNA Replication
 DNA opens up and makes a complete
copy of itself – necessary during mitosis and meiosis  New nucleotides float in and pair in a complementary fashion – A to T, C to G and vice versa…  Since are using one of original uprights of DNA ladder to join to, this process is referred to as SEMICONSERVATIVE

Figure 5.30 The DNA double helix and its replication

Summary of flow of genetic info…
 RNA  protein
transcription translation

 Transcription – in nucleus of cell; opens up DNA double
helix, copies section needed for protein manufacture, this makes messenger RNA (mRNA)  Translation -- mRNA travels out of nucleus to cytoplasm to a ribosome (site of protein manufacture); ribosomal RNA (rRNA) anchors the transcript in the ribosome, transfer RNA (tRNA) brings in correct amino acid by reading 3 amino acids at a time (codon)

Figure 5.28 DNA RNA  protein: a diagrammatic overview of information flow in a cell

Decoding mRNA code…

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